V groove pulley centrifugal clutch



Sept. 3o, 1952 M H DAVIS `V GROOVE PULLEY CENTRIFUCL CLUTCH l T E w S .S 2

Filed June 15, l1949 .Aria

Sept. 30, 1952 M. H. DAVIS v GROOVE PULLxsYpENTRIFUGAL CLUTCH Filed June 15, 1949 2 SHEETS-SHEET 2 A y Snventor MAR/0N H. DAV/s Gttomeg Patented sept. so, 1952` if 2,612,054"- i a circuirisoribingr spring; andingoing from idling to maximum operating position, the Ystretching of the spring is substantially'proportional 'to' the` circumferences at idling? a'ridmelxignil V'efrating positions. As these devices'are',particularly s'it! able for small installations' under" shfednditions' thev percentage-- s tretcliing''V of' th" slidingv`v becomes large. For' example; thei stretehfria' 11/2l inch diameter circlefto'a 2'1/2" inchfdi'an'ietr' circle' amounts to 662/3fper' centirceals'in'ciif cum'ference, and this 'stretch 'is 'super'pslei r"o'nf'tlie initial bias of the springrreqiredfto'hold'the wedges at their central in'operatiieiosit a result, the'Spring'maybecomestretcie i its elastic limit or become ffatig'ud-andlose' part of its restoring:force'orfinitialbias This changes the engaging speed `of the clutch'ar'id" its'fothe'v characteristics.Y A further di'ieulty'fsoriietimesencountered"iniv a three wedge clutchdsithat occasionally oiefof the-Wedges become'lodg'edor stuckin expanded position. This@apparentlyisnecause"tlievxie'deesj do `not always arrange themselves;symmetrically in expanded .positiori'sof'that' whentl'iey rmiife toward their centralfpositio'ri" they soietin'ies; have becometurned abo1it190 andbecoinestck'.' Thisisr especially-f' liable to",happen"'wherthe l springy becomes fatigued. Al'soj'th'eir'unsfymiet-J rical position causes Vibration and excessive wea." The use lof guidesfnotgonlyfincresesthcestfoi construction of f the fdelicefbiit introduces acidi? tional wearing surfaces'and 'incra'ses'th ii'a'loility?v of stickingat 'such*surfaces:` .flioj iiii'edl at? taching the 'Wedgestothe rspring "tr'ierelyl "BIE'alf vates the stretchingorftheplng'ffbeeeseithis i y J z K K does not prevent j the wedges" iremarrangln plhed'by'btilglf themselves unsymmetrically'in Aexpanded. porsi.;v .'.ll'inproveient alldi d tion, and uneven stretchingfof thsprifres'ltlsi ticil"vaiugiriL 'fcoibildclutchla d.I Accordingly amongthe"objectsi'offthie'invn# ralticf'cl'rive` I-lti'V ,tHeymSfbeemployed iix` tion is the provi'sioniofy afcor'nbine' centrifugal' 50k a,Sclutcli"devicefin"which'thleiiectiievdepbh ofI clutch and variable ratio transmissim'zmember themvy grooveofrphe' pmleyis sub'sttiiiythf which is more positive andcertaiiirfits"'actin;" saias`- tiiefthicknessfofjthv bel-'t`Av has increased durability; andwhiclilretsits Variable ratio'driverange'isfab K t' operating characteristicssubstantiliyunclihei* vThe*irii'lentio'y i1l.be"de`s'cribe 1 overa'loiig'perioiof use.m f 55' tll'iwoiinetin stantially constant charatistics througho life? u Y.

Figure 6 is a view similar toFigure l of a` modiiication,

4, been attained, the wedges 18a and I8b are driven radially outward by centrifugal force against the centripetal force of spring 2l and due to the wedging action of the dog sections between abutment d and face IE, they force the pulley section 8 toward the pulley section :l to form a driving engagement with the belt. As the depth of the V groove between the pulley sections is substantially greater than the thickness or" the V belt, a further increase ingspeed of the pulley forces the vwedges radially outward a further amount and the belt moves radially outward,

Figure 7 is an end view of Figure 6 as seen i e from the left, and Y o Figures 8 and 9 show the dog sections and manual operator in two different positions.

Referring to the drawing, Figures 1 to 4, there" is shown a sleeve or core member I of suitable material-adapted to receive a driving shaft 2.0i a motor, and which is securedto rotate with the shaft by any suitable connection. The sleeve has a plate 4 secured thereto at one end in any suitable manner to rotate therewith. At the other end is secured a flange 5, as by a set screw or the like, this latter flange having a conical face 1 on one side. Another ilange 8 with a con- Vex frusto conical i'ace 9 has a bore II which receives the sleeve I, and a spline i2 therein receives the key I3 so that sleeve I and nange 8 rotate together, while flange 8 is capable of movement axially of the sleeve. If desired, ange 8 may have an integral sleeve or bearing I4 yengaging the sleeve to limit or control wobbling action Athereof on the sleeve I. Flanges 5 and 8 and their convex frusto-conical faces l, 9 respectively constitute a V groove pulley designated generally by A, adapted to receive an endless V belt B. Pulley section 8 hasV a concave .rusto-conical face AI5 opposite face 9.

A centrifugal dog member indicated generally by numeral I8, is composed of two semicircular sections Iaand I8b which provide a conical 'face I9 disposed at substantially the same apex angle as the face I5 of the pulley section 8. The dog members or wedges Ia, I8b are disposed around sleeve I with their iiat or normal vface 2| adapted to engage abutment 4. and their cont,

icalface I il adapted to engage pulley face I5. The dog has a groove 22 formed in its periphery,

' and at the ends of each section the groove edges are rounded as indicated at 2 3. The edge 2li of the dog also is rounded.

The abutment plate 4 carries two pegs 25/and sume this ,shape without pinching or binding thev spring. The distance of the abutment ik vfrom pulley section 5, `the axial height or thickness of the conical dog I8,and the thickness of pulley section 8 are such, that when the dog sections are at their collapsed or radially innermost position as shown in Figure l, the distance between pulley sections 5 and 8 is sufficient to prevent driving engagement with the V belt B. In such position the V belt may rest on the sleeve I.

,. In operation when a predetermined speed has thus providing a drive on a gradually increasing diameter. The variable ratio drive thus provided tendsto accommodate itself to an equilibrium in which the belt tension is proportional to thgposition of the wedges.

In operation, the spring 2 has an initial bias so as tocause the wedges to stay in their central position. Using a three section wedge, the spring must stretch in expanded position in proportion to the circumference in such position. However, bythe provisionV oi only two wedge sections, the spring is required to stretch only in proportion to the difference in diameters. For example, in going from a diameterof 11/2 inches collapsed position to2 1/2 inches expanded position, when two 4wedges are used, the spring stretches (21/2-l1/2) 2= 2 inches. If three wedges were used the spring stretch would be or 3.14 inches. There is thus a one-third reduction in stretch. VThis greatly reduces fatigue and loss of life in the spring. *l

The pegs25, 25 serve as an anchor for the spring to conne the movement of the dog sections so that they tend to keep in symmetrical spaced relation in their spread position, while maintaining a; substantially uniformly distributed strain on the spring between anchors. The particular type of anchor employed, which may be called 'a friction anchor, automatically allows the tension on the spr-ing in the two lobes to be equalzed; and thus eliminates manual adjustor nutation of pulley section 8 on sleeve I and prolongs `the life. of'thekeyed joint therewith.

The combined clutch and variable speed drive device is of particular. value on motorcycles,

motor bicycles and other small motor propelled Some motor bicycles require the motor to be started by pedallingthe bicycle, and for such installation I provide a. manual engaging clutch device which will nowbe described. Referring to Figures to 9, the plate "li has pins BI, 3l' rotatably ,iournaledtherein andcarrying spreaders or cams 33, 34 respectively ontheir ends. The pins are` so located' that the-cams come between thev dogfsec'tions .18a and i317, and when'lthe cams are radially .arranged as shown in Figure 8 they allow sufficient `collapse of the centrifugal wedges so that. there. is no driving engagement between the beltand pulley sections. However, when arranged in the angular position as shownin Figure `9, the cams'fspread the dog sections sufficiently to move pulley section 8 to the-righty (Figure di and thus establish a driving engagement; with .thebelt In this position when the bicycle is advanced by pedalling, the. driven pulley oni the bicycle- (which now becomes the driving pulley)fti1rns-.the pulley A` to crank' the moto-rf- 'I'hef-spreaders-S-B, 3ft are manually Positioned to-cause clutchv engagement, and I prefer tol provide an automatic disengagement thereof the wedge sections which becomes operative when the motorstarts. l This feature now' will lbe describedz Acap 35 isfreceived over plate 4 and may'have turned V over-'edges 36- to` retain itin position while allowing-rotation of the-cap. Pins 31; 3l vhave arms 31,938" at `their exteriorends and guide pins- 39, '4l 7are` located near the outer ends of the arms. These guide pins passyinto openings *or recesses 431,44 respectively in the capl 35. `These recesses are illustrated as triangular in shape with an apex angle of about 35'.

Theoperati'on will now be described. To start the motor, thecap is manually rotated in the direction of the arrow in Figure '7 to shift the arms' 3l 3S. tola'pproximatel'y a; rightV angle: position, as shown by dot and dash lines therein. This turns the spreaders 33,` i4Vv tothe position shown in Figure 9 and expands the wedge sections I 3a, leb, so as to shiftpulley section 8 to the righ'tjandu form a driving engagement' with the belt.- Now'upori pedallingthe motor-bicycle the rearwheel is driven through thev coaster brake, which in'turn drives pulley A and shaft 2 to turn over and start the motor. When the motor starts the speed of rotation of the pulley develops a force' sufficient to immediately restore.

arms 37; `Sii; to theirfradial positions (shown in full'lines in Figure '7), and to turn the cap member 35 therewith, so that there is no restraint on the motor. The device then is capable of serving as a variable ratio drive and is in condition to automatically declutch when the motor speed falls below clutching speed.

If desired, the manual clutching device may be remotely operated by means of a wire or other connection with a lost motion connection therewith to allow restoration movement. The manual clutching device may1 be applied to a clutch having three or more wedges, but for the reasons hereinabove stated, it is preferably used in conjunction with semicircular wedges.

I claim as my invention:

1. A centrifugal clutch comprising: a shaft; a pair of relatively axially movable pulley sections on the shaft providing a V-groove therebetween for reception ofa V-belt; a plurality of centrifugal wedge members for relatively shifting said pulley sections; and spreader members located between said wedge members, said spreader members having a normally inoperative position, and being movable to a position wherein they expand the Wedge members to shift said pulley sections to belt engaging position.

2. A centrifugal clutch as specified in claim 1 having centrifugally operated means for returning said spreaders to normally inoperative position.

8. A centrifugal clutch as specified in claim 1 wherein said spreader members` comprise cams. 4. A centrifugal clutch as specified in claim 1 wherein said spreader members are connected to rotatable arms, and a rotatable cover plate has means engaging said arms for opearting said spreader members.

5. A centrifugal clutch comprising: a shaft; a pair of relatively axially movable pulley sections oirth-e shaft providingaM-greove therebetween for reception of ra; .tt-liel'tf a'plurality. of: centrifugally operated wedgemembersfor relatively shifting said-pulleysectionstoward each other in 'expanded-position; rneansiy for Positively moving saidwed'ge members-l tofianf expanded position;

' manually operated means; for: operating: said. lat'- ter4 means; and fcentrifugally operated means. for mov-ing said 'manually foperatedi means.' to. inoperativ'eiposition:5 j

6. vvA centrifugal clutch. comprising: a pairof relatively axially movable. pulleyfsecti'onslproviding'.a..Vg-roove therebetween for-reception of" a V-belt; one of said sectionshaving a' concave.- conicalicam face;l an-` abutment member having a cooperating l cani. face. opposite J-'safdi concaveconicaliface. a pair. only*` of semi-circular frustoconicalrwedge members between; saidi abutment member and a. pulley section. cooperating; there- Wi'tli"r.and movable .outwardlyl-bly 'centrifugal action .to move onefof. said` pulleyl sectionstow-ard thefother'- pulley.` section; ancirc'umscribing spring yie'ldingly` confining said wedge; members;` and means-extending froml onetofthe cam. faces 'to anchorsaid spring. between. the wedge members.

1.7. Afcen'trifugal clutch asspecifiedin claim 6 wherein said-anchor means 'frictionallyf engage anddepressthespring between saidawedge membei-5;.. i-. 1..' 1.8? A'centrifugai clutch aszspecified'iir claim Z- wherein saidwedge members: have a peripheral grooveytoireceive saidspring, and the' ends of said groove arerounded'.' f

Acentrifugal clutch comprising:l ai pair of relatively axially movable pul-le'yfsections providing aYV-groove therebetweenfor-reception cfa V-belt;'an abutment' platea pluraliltyof centrifugal wedge members betweenthe abutment plate and one of the pulley sections for relatively shifting said pulley sections; spreader members positioned between adjacent ends of the wedge members in collapsed position of the wedge members, said spreader members having a normal inoperative position, and being movable to an operative position wherein they spread the wedge members to shift said pulley sections to belt enof a V-belt; an abutment plate; a plurality of centrifugal wedge members 'between the abutment plate and one of the pulley sections for relatively shifting said pulley sections; rotatable spreader members positioned between adjacent ends of the wedge kmembers in collapsed position thereof, said spreader members having a normal inoperative position, and being movable toa position wherein they spread the wedge members to shift said pulley sections to belt engaging position; a rotatable plate; and arms secured to said spreader members and rotatable therewith, said arms having a lost motion interengagement with said plate and operative upon rotation of the plate in one direction to shift said spreaders to wedge expanding position, and

develop a force to return the spreader members to inoperative position upon rotation of the pulley sections in one direction.

11. A centrifugal clutch as specified in cla-im 10 wherein said rotatable plate has a ange engaging said abutment retaining the plate against separation from said abutment.

12. A device of the class described comprising a shaft; a first pulley section secured to the shaft providing a conical belt-engaging face; an axially floating pulley section having a cam face mounted on the shaft torotate therewith and providing a complementaryconical belt-engaging face forming a V-groove with the first pulley section adapted to receive a V-belt, said V- groove having a depth greater than the thickness of the V-belt; an abutment plate on said shaft adjacent said oating pulley section having an opposing cam face, the opposing cam faces of the pulley and abutment converging radially outward; a. pair only of radially movable wedge-shaped segments normally located in radially inward position about the shaft to allow said pulley sections to disengage from the V- belt; said segments having outwardly converging opposite cam faces, and upon rotation of said shaft above a predetermined speed, being guided by the cam faces of the oating pulley and abutment in moving radially outwardly to maintain simultaneous Wedging engagement with the abutment cam face and pulley cam face to move said belt-engaging faces of the pulley sections in driving contact with the V-belt; the maximum axial distance between the opposite cam faces of a wedge segment measured at any given radius when the segments are at their normally radially inward position being less than the axial distance between the pulley cam face and abutment cam face measured at the same given radius when the floating pulley sections is disengaged from the belt; and means forming a driving engagement between said segments and radially-movable relativel to said shaft and circumferentially movable relative to each other and to the shaft; and a -circumscribing spring yieldably confining said wedgemembers about said Shaft. I f.

14. A centrifugal clutch as specified in claim 13 having means ori-said abutment engaging said spring between wedge members.

v MARION H. DAVIS.

REFERENCES CITED Thel following references are of record in th file of this patent:

' UNTEn `STATES PATENTS Number Name Date 1,077,728 Mann Nov. 4, 1913 1,215,513 Fichter Feb. 13, 1917 2,065,432 Delay- A Dec. 22, 1936 2,104,074 Erbach Jan. 4, 1938 2,180,217 Thomas Nov. 14, 1939 2,251,588 Gilbert Aug. 5, 1941 2,453,580 Lusk Nov. 9, 1948 2,496,061 Miner Jan. 31, 1950 2,496,201

Dodge Jan. 31, 1950 

